Frederick Edward Grey Ponsonby, 1st Baron Sysonby (16 September 1867 – 20 October 1935), was a British soldier and courtier.

After attending Eton, Ponsonby received a commission in the Duke of Cornwall's Light Infantry as a second lieutenant.

He also held several court positions, notably as Equerry-in-Ordinary to Queen Victoria from 1894[2][3] to 1901, as Assistant Keeper of the Privy Purse and Assistant Private Secretary to Queen Victoria from 1897[4][5] to 1901, to King Edward VII from 1901 to 1910 and to King George V from 1910[6][7] to 1914; as Keeper of the Privy Purse from 1914[8][9] to 1935, and as Lieutenant Governor of Windsor Castle from 1928 to 1935.

[17][18] Lord Sysonby married Victoria, daughter of Colonel Edmund Hegan Kennard, on 17 May 1899, at the Guards' Chapel, Wellington Barracks.

They had three children: Lord Sysonby died in London in October 1935, aged 68, only four months after his elevation to the peerage, and was cremated at Golders Green Crematorium.

Lady Sysonby, who died in 1955, was denied a pension by George V and was required to vacate St. James’s Palace, where she had lived with her husband throughout their married life.

His grandfather, Frederick Ponsonby, was badly wounded at the Battle of Waterloo, but survived to become a British Army general.